1. Field of the Invention
This invention relates to a power supply circuit and, more particularly, to a power supply circuit for use in a combined audio system.
2. Description of the Prior Art
A combined audio system is well known, a typical system comprising a combination stereo signal apparatus for processing and reproducing audio signals. Generally, such combination stereo apparatus includes a main audio apparatus such as a signal receiver including an amplifier and at least one loudspeaker, and auxiliary audio apparatus such as a record player and/or a tape deck. In some combination stereo apparatus, an automatic de-energizing mechanism is arranged by which the record player or the tape deck is de-energized to be non-operative at the end of play of the recorded medium (e.g. record or tape) and then the receiver is de-energized to be non-operative. With this mechanism, even if the user falls asleep during the operation of the system, the record player and the receiver are conveniently de-energized (or shut-off) to be non-operative at the end of play of the recorded medium.
However, when the tape deck including an automatic shut-off mechanism is used in the combination stereo apparatus exhibiting the automatic de-energizing mechanism, the tape deck normally is de-energized at the end of play of the tape, but the receiver is not concurrently de-energized and thus remains operative. Accordingly, the conventional combination stereo apparatus has the disadvantage that the automatic de-energizing operation cannot be performed during the tape reproducing mode.